It is sometimes necessary or desirable to invasively monitor the blood pressure of a patient at two locations within the cardiovascular system. When this is done, it is necessary to provide continuous flow of an appropriate solution, such as a saline solution, to both locations to keep the conduits patent.
To reduce the cost of the pressure-measuring system, a single pressure transducer can be used to measure the pressure at both locations. This is accomplished by a suitable switching system which switches the transducer from one circuit to the other as may be required so that the pressure at the two locations can be sequentially measured.
Although this is a sound concept, prior art systems implementing this concept have certain disadvantages. For example, in some systems of this type, there is no flow of the solution through the transducer, i.e., the transducer is in a deadend path. It is believed that this increases the likelihood of problems with infection. In another system of this type, flow through the transducer is provided. However, in this latter system, the flow of solution to one of the locations is shut off when the transducer is switched to monitor the pressure at another of the locations. Thus, problems with patency of the lines is more likely to develop. Accordingly, neither of these systems provides both flow through the transducer and continuous flow of solution through both lines leading to the patient, regardless of which pressure is being monitored.